package io.trygvis.android.bt;

import android.bluetooth.BluetoothGatt;
import android.bluetooth.BluetoothGattCallback;
import android.bluetooth.BluetoothGattCharacteristic;
import android.bluetooth.BluetoothGattDescriptor;
import android.util.Log;

import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Queue;

import io.trygvis.android.F2;
import io.trygvis.android.F3;
import io.trygvis.android.Function;

import static io.trygvis.android.bt.BtPromise.EventType.onCharacteristicChanged;
import static io.trygvis.android.bt.BtPromise.EventType.onCharacteristicRead;
import static io.trygvis.android.bt.BtPromise.EventType.onCharacteristicWrite;
import static io.trygvis.android.bt.BtPromise.EventType.onConnectionStateChange;
import static io.trygvis.android.bt.BtPromise.EventType.onDescriptorRead;
import static io.trygvis.android.bt.BtPromise.EventType.onDescriptorWrite;
import static io.trygvis.android.bt.BtPromise.EventType.onDirect;
import static io.trygvis.android.bt.BtPromise.EventType.onFailure;
import static io.trygvis.android.bt.BtPromise.EventType.onFinally;
import static io.trygvis.android.bt.BtPromise.EventType.onReliableWriteCompleted;
import static io.trygvis.android.bt.BtPromise.EventType.onServicesDiscovered;

public class BtPromise {
    private final static String TAG = BtPromise.class.getSimpleName();
    private final List<BtCallback> actionQ = new ArrayList<>();
    private final Queue<BtCallback> failureQ = new ArrayDeque<>();
    private final Queue<BtCallback> finallyQ = new ArrayDeque<>();

    private static final PromiseResult waitForNextEvent = new WaitForNextEvent();
    private static final PromiseResult stop = new Stop();

    private Boolean stopOnFailure;

    public static class PromiseResult {
        private PromiseResult() {
        }

        public static PromiseResult waitForNextEvent() {
            return waitForNextEvent;
        }

        public static PromiseResult continueDirectly(Object value) {
            return new ContinueDirectly(value);
        }

        public static PromiseResult stop() {
            return stop;
        }

        public static PromiseResult detour(BtPromise promise) {
            return new Detour(promise);
        }
    }

    private static class WaitForNextEvent extends PromiseResult {
    }

    private static class ContinueDirectly extends PromiseResult {
        private final Object value;

        private ContinueDirectly(Object value) {
            this.value = value;
        }
    }

    private static class Stop extends PromiseResult {
    }

    private static class Detour extends PromiseResult {
        final BtPromise promise;

        private Detour(BtPromise promise) {
            this.promise = promise;
        }
    }

    private boolean stopOnFailure() {
        if(stopOnFailure != null) {
            boolean b = stopOnFailure;
            stopOnFailure = null;
            return b;
        }
        return false;
    }

    public BtPromise ignoreFailureForNext() {
        stopOnFailure = true;
        return this;
    }
    
    public synchronized BtPromise onConnectionStateChange(F3<BluetoothGatt, Integer, Integer, PromiseResult> callback) {
        actionQ.add(new BtCallback(stopOnFailure(), "onConnectionStateChange") {
            @Override
            public PromiseResult onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
                return callback.apply(gatt, status,newState);
            }
        });
        return this;
    }

    public synchronized BtPromise onServicesDiscovered(Function<BluetoothGatt, PromiseResult> callback) {
        actionQ.add(new BtCallback(stopOnFailure(), "onServicesDiscovered") {
            @Override
            public PromiseResult onServicesDiscovered(BluetoothGatt gatt) {
                return callback.apply(gatt);
            }
        });
        return this;
    }

    public synchronized BtPromise onCharacteristicRead(F2<BluetoothGatt, BluetoothGattCharacteristic, PromiseResult> callback) {
        actionQ.add(new BtCallback(stopOnFailure(), "onCharacteristicRead") {
            @Override
            public PromiseResult onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) {
                return callback.apply(gatt, characteristic);
            }
        });
        return this;
    }

    public synchronized BtPromise onCharacteristicWrite(F2<BluetoothGatt, BluetoothGattCharacteristic, PromiseResult> callback) {
        actionQ.add(new BtCallback(stopOnFailure(), "onCharacteristicWrite") {
            @Override
            public PromiseResult onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) {
                return callback.apply(gatt, characteristic);
            }
        });
        return this;
    }

    public synchronized BtPromise onCharacteristicChanged(F2<BluetoothGatt, BluetoothGattCharacteristic, PromiseResult> callback) {
        actionQ.add(new BtCallback(stopOnFailure(), "onCharacteristicChanged") {
            @Override
            public PromiseResult onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) {
                return callback.apply(gatt, characteristic);
            }
        });
        return this;
    }

    public synchronized BtPromise onDescriptorRead(F2<BluetoothGatt, BluetoothGattDescriptor, PromiseResult> callback) {
        actionQ.add(new BtCallback(stopOnFailure(), "onDescriptorRead") {
            @Override
            public PromiseResult onDescriptorRead(BluetoothGatt gatt, BluetoothGattDescriptor descriptor) {
                return callback.apply(gatt, descriptor);
            }
        });
        return this;
    }

    public synchronized BtPromise onDescriptorWrite(F2<BluetoothGatt, BluetoothGattDescriptor, PromiseResult> callback) {
        actionQ.add(new BtCallback(stopOnFailure(), "onDescriptorWrite") {
            @Override
            public PromiseResult onDescriptorWrite(BluetoothGatt gatt, BluetoothGattDescriptor descriptor) {
                return callback.apply(gatt, descriptor);
            }
        });
        return this;
    }

    public synchronized BtPromise onReliableWriteCompleted(Function<BluetoothGatt, PromiseResult> callback) {
        actionQ.add(new BtCallback(stopOnFailure(), "onReliableWriteCompleted") {
            @Override
            public PromiseResult onReliableWriteCompleted(BluetoothGatt gatt) {
                return callback.apply(gatt);
            }
        });
        return this;
    }

    public synchronized BtPromise onReadRemoteRssi(F2<BluetoothGatt, Integer, PromiseResult> callback) {
        actionQ.add(new BtCallback(stopOnFailure(), "onReadRemoteRssi") {
            @Override
            public PromiseResult onReadRemoteRssi(BluetoothGatt gatt, int rssi) {
                return callback.apply(gatt, rssi);
            }
        });
        return this;
    }

    public synchronized BtPromise onDirect(Function<Object, PromiseResult> callback) {
        actionQ.add(new BtCallback(stopOnFailure(), "onDirect") {
            @Override
            public PromiseResult onDirect(Object value) {
                return callback.apply(value);
            }
        });
        return this;
    }

    public synchronized BtPromise onFailure(Runnable callback) {
        failureQ.add(new BtCallback(stopOnFailure(), "onFailure") {
            @Override
            public void onFailure() {
                callback.run();
            }
        });
        return this;
    }

    public synchronized BtPromise onFinally(Runnable callback) {
        finallyQ.add(new BtCallback(stopOnFailure(), "finally") {
            @Override
            public void onFinally() {
                callback.run();
            }
        });
        return this;
    }

    public String toString() {
        StringBuilder s = new StringBuilder("Queue: ");

        Iterator<BtCallback> it = actionQ.iterator();

        int i = 0;
        while (it.hasNext()) {
            BtCallback c = it.next();
            if (i > 0) {
                s.append(", ");
            }
            s.append(c.name);
            i++;
        }

        return s.toString();
    }

    BtBluetoothGattCallback asCallback(String address) {
        return new BtBluetoothGattCallback(address, actionQ, failureQ, finallyQ);
    }

    enum EventType {
        onConnectionStateChange,
        onServicesDiscovered,
        onCharacteristicRead,
        onCharacteristicWrite,
        onCharacteristicChanged,
        onDescriptorRead,
        onDescriptorWrite,
        onReliableWriteCompleted,

        onReadRemoteRssi,

        onDirect,
        onFailure,
        onFinally,
    }

    private static PromiseResult callCallback(EventType key, BluetoothGatt gatt,
                                              BluetoothGattCharacteristic characteristic,
                                              BluetoothGattDescriptor descriptor, int status, int newState,
                                              BtCallback btCallback, Object value) {
        switch (key) {
            case onConnectionStateChange:
                return btCallback.onConnectionStateChange(gatt, status, newState);
            case onServicesDiscovered:
                return btCallback.onServicesDiscovered(gatt);
            case onCharacteristicRead:
                return btCallback.onCharacteristicRead(gatt, characteristic);
            case onCharacteristicWrite:
                return btCallback.onCharacteristicWrite(gatt, characteristic);
            case onCharacteristicChanged:
                return btCallback.onCharacteristicChanged(gatt, characteristic);
            case onDescriptorRead:
                return btCallback.onDescriptorRead(gatt, descriptor);
            case onDescriptorWrite:
                return btCallback.onDescriptorWrite(gatt, descriptor);
            case onReliableWriteCompleted:
                return btCallback.onReliableWriteCompleted(gatt);

            case onDirect:
                return btCallback.onDirect(value);
            case onFailure:
                btCallback.onFailure();
                return null;
            case onFinally:
                btCallback.onFinally();
                return null;
            default:
                Log.w(TAG, "Unknown callback: " + key);
                return null;
        }
    }

    static class BtBluetoothGattCallback extends BluetoothGattCallback {

        private final String address;
        private List<BtCallback> actionQ;
        private ListIterator<BtCallback> it;
        private ArrayDeque<BtCallback> failureQ;
        ArrayDeque<BtCallback> finallyQ;
        private List<String> events = new ArrayList<>();

        private BtBluetoothGattCallback(String address, List<BtCallback> actionQ, Queue<BtCallback> failureQ, Queue<BtCallback> finallyQ) {
            this.address = address;
            this.actionQ = new ArrayList<>(actionQ);
            this.failureQ = new ArrayDeque<>(failureQ);
            this.finallyQ = new ArrayDeque<>(finallyQ);
            this.it = actionQ.listIterator();
        }

        void onEvent(EventType key, String values, BluetoothGatt gatt, BluetoothGattCharacteristic characteristic,
                     BluetoothGattDescriptor descriptor, int status, int newState, Object value) {
            boolean success = status == BluetoothGatt.GATT_SUCCESS;
            events.add(key + "(" + values + "), success=" + success);

            Log.i(TAG, "event: " + key + "(" + values + "), success=" + success);

            if (!success) {
                doFailure();
                return;
            }

            BtCallback btCallback;
            synchronized (this) {
                if (!it.hasNext()) {
                    Log.d(TAG, "All Bluetooth actions are done");

                    doFinally();
                    return;
                }

                btCallback = it.next();
                Log.i(TAG, "Executing bt action: " + btCallback.name);
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    // ignore
                }
            }

            try {
                PromiseResult result = callCallback(key, gatt, characteristic, descriptor, status, newState, btCallback,
                        value);

                if (result instanceof Stop) {
                    Log.i(TAG, "The chain want to stop.");
                    doFinally();
                } else if (result instanceof Detour) {
                    Log.i(TAG, "Adding detour");
                    BtPromise promise = ((Detour) result).promise;
                    events.add("detour " + promise.actionQ.size());
                    if (!promise.failureQ.isEmpty()) {
                        Log.i(TAG, "Ignoring " + promise.failureQ.size() + " items from the failure Q");
                    }
                    if (!promise.finallyQ.isEmpty()) {
                        Log.i(TAG, "Ignoring " + promise.finallyQ.size() + " items from the finally Q");
                    }

                    synchronized (this) {
                        for (BtCallback cb : promise.actionQ) {
                            it.add(cb);
                        }
                    }
                } else if (result instanceof ContinueDirectly) {
                    value = ((ContinueDirectly) result).value;
                    onEvent(onDirect, "value=" + value, null, null, null, BluetoothGatt.GATT_SUCCESS, 0,
                            value);
                    return;
                }

                if (!it.hasNext()) {
                    Log.i(TAG, "The queue is empty");
                }
            } catch (NotOverriddenException e) {
                Log.w(TAG, "Unexpected callback by listener: " + key);
                doFailure();
            }
        }

        private void doFailure() {
            StringBuilder msg = new StringBuilder();

            msg.append("Address: ").append(address).append("\n");
            msg.append("Expected events: \n");
            for (BtCallback cb : actionQ) {
                msg.append("-  ").append(cb.name).append("\n");
            }

            msg.append("Actual events: \n");
            for (String event : events) {
                msg.append("-  ").append(event).append("\n");
            }

            Log.w(TAG, msg.toString());

            Log.w(TAG, "Executing " + failureQ.size() + " failure handlers");

            for (BtCallback callback = failureQ.poll(); callback != null; callback = failureQ.poll()) {
                try {
                    callCallback(onFailure, null, null, null, 0, 0, callback, null);
                } catch (NotOverriddenException e) {
                    return;
                }
            }

            doFinally();
        }

        private void doFinally() {
            actionQ.clear();

            Log.w(TAG, "Executing " + finallyQ.size() + " finally handlers");

            for (BtCallback callback = finallyQ.poll(); callback != null; callback = finallyQ.poll()) {
                try {
                    callCallback(onFinally, null, null, null, 0, 0, callback, null);
                } catch (NotOverriddenException e) {
                    return;
                }
            }
        }

        // -----------------------------------------------------------------------
        //
        // -----------------------------------------------------------------------

        @Override
        public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
            onEvent(onConnectionStateChange, "status=" + status + ", newState=" + newState, gatt, null, null, status, newState, null);
        }

        @Override
        public void onServicesDiscovered(BluetoothGatt gatt, int status) {
            onEvent(onServicesDiscovered, "status=" + status, gatt, null, null, status, 9, null);
        }

        @Override
        public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
            onEvent(onCharacteristicRead, "status=" + status + ", characteristic=" + characteristic.getUuid(), gatt, characteristic, null, status, 0, null);
        }

        @Override
        public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
            onEvent(onCharacteristicWrite, "status=" + status + ", characteristic=" + characteristic.getUuid(), gatt, characteristic, null, status, 0, null);
        }

        @Override
        public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) {
            onEvent(onCharacteristicChanged, "characteristic=" + characteristic.getUuid(), gatt, characteristic, null, BluetoothGatt.GATT_SUCCESS, 0, null);
        }

        @Override
        public void onDescriptorRead(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status) {
            onEvent(onDescriptorRead, "status=" + status + ", descriptor=" + descriptor.getUuid(), gatt, null, descriptor, status, 0, null);
        }

        @Override
        public void onDescriptorWrite(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status) {
            onEvent(onDescriptorWrite, "status=" + status + ", descriptor=" + descriptor.getUuid(), gatt, null, descriptor, status, 0, null);
        }

        @Override
        public void onReliableWriteCompleted(BluetoothGatt gatt, int status) {
            onEvent(onReliableWriteCompleted, "status=" + status, gatt, null, null, status, 0, null);
        }

        @Override
        public void onReadRemoteRssi(BluetoothGatt gatt, int rssi, int status) {
//                onEvent(onReadRemoteRssi, "status=" + status, gatt, null, null, status, 0);
        }
    }
}